Abstract: A loudspeaker having means for acoustically impeding excursion of the transducer diaphragm and means for acoustically attenuating the output of acoustic vibrations of frequencies above a preselected frequency. The loudspeaker includes first and second subchambers separated by a dividing wall in which the transducer is mounted. A first port acoustically couples the first subchamber with the second subchamber and a second port acoustically couples the second subchamber with the outside environment surrounding the loudspeaker.

Abstract: A muffler comprising a casing, a defining member for defining at least two resonance chambers in the casing, and a pipe for flowing a gas therethrough. Each of the resonance chambers has a different resonance frequency, and the pipe is communicated with each resonance chamber. Therefore, a plurality of noise frequencies can be suppressed.

Abstract: A speaker system especially designed to improve the characteristics of low sound bands. The speaker system desirably includes a partition dividing the interior of a cabinet into a speaker chamber and a resonance chamber, and two radiation ports. One radiation port is formed on the partition and the other one on the walls of the resonance chamber which do not face each other.

Abstract: A disposable shield for stethoscope heads, preventing the transfer of disease or other contaminants by repeated use of the stethoscope. The shield or envelope is formed from a single piece of plastic material in which the sides are folded toward each other, thereby defining two top portions overlying a bottom portion. The edges are sealed as by heat sealing, thereby defining an envelope or shield. In a preferred embodiment, the shields are formed and maintained in a ribbon or array, maintained in the form of a roll within a container or the like. Adjoining shields are interconnected at the heat sealed areas which may be perforated for ease of separation.

Abstract: Going inwardly from the outside, the walls of the housing comprise a multi-ply slab, one or more layers of elastomer coating, a plate of amorphous bitumen, and acoustic screens constituted by substantially contiguous parallel tubes which are filled with a solid material which is in the divided state and highly compacted, e.g. sand, or particles of graphite, or grains of silica. In addition, the enclosures include one or more blocks behind the loudspeakers and made of cellular foam with channels passing therethrough parallel to the axes of the loudspeakers.

Abstract: A generally tubular cylinder of resilient material such as a silicon rubber, for mounting over a hearing aid, or ear plug, so as to provide two gaskets which seal the hearing aid, or ear plug, against the skin of the ear canal and stabilize it against movement in the ear canal thereby suppressing acoustical feedback. The cylinder is further shaped to provide a tab which extends to the exterior of the ear canal so that it can be easily grasped by the user to remove the hearing aid.One of the ends (or gaskets) of the hearing aid harness may be lengthened to extend beyond and away from that end of the hearing aid which houses the speaker.

Abstract: An acoustic insulating board of foam with structured bulge-forming surface in the form of regions (I, II) of different thickness. In order to obtain differing acoustic efficiency, the acoustic insulating board comprises plurality of individual boards (1) arranged one above the other, which boards are compressed in the regions (I) of lesser thickness and are fused together on their surface. In the regions (II) of larger thickness, the boards lie loosely on one another so that a top side facing in the direction of the structural bulging of a central individual board (1) is profiled in the regions of greater thickness.

Abstract: This invention is concerned with a hearing aid including a microphone, an adjustable amplifier, and an acoustic transducer positioned within a first, large acoustic chamber defined by an in-the-ear housing. The acoustic transducer is in communication with a sound outlet passage which leads into the user's ear canal. The acoustic transducer includes a sound generating diaphragm driven by an acoustic driver. The diaphragm and driver are mounted in the acoustic transducer, with the diaphragm dividing the transducer into second and third acoustic chambers. A vent passage is provided between the first and third acoustic chambers. An acoustic resistance is mounted in the vent passage to modify the operating characteristics of the hearing aid.

Abstract: The invention relates to an exhaust gas muffler for a two-stroke engine of a portable handheld tool such as a chain saw. The exhaust gas muffler includes a catalyzer wherein high exhaust gas temperatures are developed because of the exothermal reaction which takes place therein. The catalyzer is located in the forward portion of a gas-tight hollow body mounted in the housing of the muffler. The hollow body has a tapered portion which extends out of the housing in the direction of the exhaust gas flow. In this way, the surface temperature of the muffler housing is reduced.

Abstract: A tuned, convoluted, stainless steel conduit assembly is especially well adapted for use in hostile environments subject to vibrations which bring on fatigue failures. To prevent the conduit from having a uniform resonance throughout its length, the convolutions have a variable wall thickness. One way this variable wall thickness may be achieved is by forming the conduit walls by wrapping stainless steel tape in successive layers to form a multiple layered wall. The width of the tape may be such that some convolutions have more layers than other neighboring convolutions. A stainless steel sleeve or stocking loosely fits over the conduit and is clamped by one or more tuning bands onto the conduit to prevent vibration of the conduit at that clamped location.

Abstract: A cover for a pre-cordial stethoscope provides protection for the stethoscope and reduces external noise contamination. The cover fits closely on the stethoscope body and includes a slot for receiving a tubular fitting which extends from the stethoscope body to transmit the monitored sounds. A shell presenting an internal vacuum chamber may be interposed between the cover and stethoscope body for enhanced noise suppression. Different embodiments of the cover are provided for adult and infant pre-cordial stethoscopes.

Abstract: A sanitary stethoscope which prevents carrying potentially infectious matter from one patient to the next comprises a modified stethoscope head or diaphragm-retaining ring and a quick-insert/quick-release replaceable diaphragm. The diaphragm is suitably held in place on the stethoscope by means of a projection on the diaphragm surface which fits into a groove on the stethoscope head or diaphragm-retaining ring, preferably with provision for magnetic attraction. Means for facilitating easy exchange of diaphragms comprise specially designed diaphragm dispensers and diaphragm storage containers or cartridges. The diaphragm dispensers may be heated to maintain the diaphragms at a temperature comfortable to the touch.

Abstract: Disclosed is an acoustic horn to aid in bulk powdered material handling particularly from trucks and railroad cars. Such acoustic horn is comprised of an external cone having a driver affix thereto. There is also an inverted internal cone contained within the external cone. There is a cylindrical throat communicating with the acoustic wave driver which extends into the internal cone, the combination of the throat extending into the internal cone contained within the external cone creates a folded horn arrangement wherein a horn of relative shortened length can achieve the desired low fundamental frequencies needed for bulk powdered material handling.Extending radially from the mouth of the external cone is a flange. Means are provided to detachably affix said flange from the flange on existing manways present on trucks and railroad cars.

Abstract: A flat, box-like muffler formed of metal upper and lower housing sections and internal gas passage defining plates has drainage holes to allow liquid that collects on the top of the muffler or on the bottom of the lower section inside the housing to drain out of the muffler. A special sound attenuation structure comprising passages pressed in the plates and support channels in the housing sections is shown.

Abstract: A speaker system provided with a globular glass enclosure to which a speaker unit is attached, wherein the enclosure is mounted elastically on a support member which consists of an elastic material and has an opening to accommodate a bottom part of the enclosure therein. The direction of the speaker unit can be freely changed under a stable posture and the occurrence of box noise due to the insufficient contact between the enclosure and the support member is prevented. In the speaker system, the enclosure may be fixed firmly at the position of its notch opening to a baffle board made of a highly rigid and/or highly oscillation-damping material for fixing the speaker unit to the baffle board, and thus the occurrence of box noise coming from the transmission of the vibration of the speaker unit to the enclosure and also coming from the deformation of the opening of the enclosure to receive the speaker unit can be prevented.

Abstract: A fireplace provided with a sound reducer is shown. The sound reducer eliminates ambient noise feeding back to the indoor through the flue system of the fireplace.

Abstract: A concrete post assembly and method of mounting same. The post assembly is supported in upright position by an inground pier in which a plurality of anchor bolts are embedded with a portion of each bolt extending upwardly above the upper surface of the pier. The post assembly includes a concrete post and a base plate rigidly secured to the bottom of the post, the base plate having a plurality of holes located so as to register with upwardly extending anchor bolts. A nut is threaded onto each anchor bolt and the post assembly is mounted on the bolts with its base plate resting on the nuts which can then be adjusted to level the plate. A second set of nuts are threaded onto the anchor bolts and tightened against the upper surface of the base plate to lock the post assembly in mounted position.

Abstract: Acoustic damping is provided by a dimensionally-recoverable article, either in single layer or constrained-layer form. The single layer, or the damping layer of a constrained-layer article, comprises a mixture of a damping component (generally having a high tangent delta value) and a hold-out component (generally having a significant crystallinity).

Abstract: An assembly for mounting an exhaust system and for connecting inlet means of said exhaust system to exhaust gas outlet means of an exhaust gas source structure of an internal combustion engine comprises a holder for carrying the exhaust system, metal bellows means fixed to the holder and secured to said exhaust gas source structure and connecting said exhaust gas outlet means to said inlet means, and a plurality of axial vibration dampers. In order to keep the deformations of the metal bellows within permissible limits and permit large forces to be taken up, six axial vibration dampers are provided, which are arranged around one or more metal bellows, only three of said vibration dampers have axes disposed in a plane, only two of said three axes are parallel to each other and the axes of the three other dampers intersect said plane and are parallel to each other or constitute a tripod having an apex spaced from said plane.

Abstract: A multipurpose calculator includes a casing having one pair of side slots made at the front on both side walls for pivotally movable connection thereto of a movable cassette block, said movable cassette block being applicable to move within 180.degree., four elongated holes made on the front end wall through the body of the casing for setting therein of a scraper, a fluorescent marker, a flat type screw driver, and a cross type screw driver respectively. The movable cassette block comprises an illuminating apparatus to provide a solar power calculator with sufficient energy for operation. The said casing includes a rectangular recess for setting thereon of a solar calculator, a cutter and a steel tape respectively mounted on both sides for specific application. According to above-described arrangement, a calculator is practical for multipurpose application.